/Engine/Source/Runtime/Core/Public/Serialization/ArchiveProxy.h
Determine if the given archive is a valid "child" of this archive. In general, this means "is exactly the same" but this function allows a derived archive to support "child" or "internal" archives which are different objects that proxy the original one in some way.
virtual bool IsProxyOf ( [FArchive](API\Runtime\Core\Serialization\FArchive) * InOther ) const